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G C Mair - One of the best experts on this subject based on the ideXlab platform.
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salinity tolerance in superior genotypes of Tilapia oreochromis niloticus oreochromis mossambicus and their hybrids
Aquaculture, 2005Co-Authors: Abu Hena Md Mostofa Kamal, G C MairAbstract:Abstract Tilapias are important candidate species for brackish water aquaculture and are increasingly cultured in coastal ponds including in polyculture with shrimp, thus creating a demand for Tilapia genotypes well suited to elevated salinities. The Nile Tilapia Oreochromis niloticus dominates freshwater Tilapia culture and has been the subject of recent efforts in genetic improvement but is one of the least salt tolerant Tilapia. Oreochromis mossambicus , are more tolerant of high salinity but tend to have lower growth rates. This study compared the culture performance of two strains of genetically improved O. niloticus (GIFT and Fishgen-selected), and two stocks of O. mossambicus (Boesmans and Kasinthula—both newly introduced to Asia directly from southeast Africa) and their hybrids. These comparisons were made over a range of fixed salinities (0, 7.5, 15, 22.5 and 30 ppt) with fish grown for 75 days in cages within concrete tanks with three replicate cages of each genotype at each salinity. Attempts to produce reciprocal hybrids failed due to very low spawning frequency in O. niloticus × O. mossambicus crosses, thus all hybrids were only of O. mossambicus maternal origin. Results for the trials were consistent across replicates and a number of interesting trends were apparent. Overall, growth was higher for all genotypes at elevated salinities with O. niloticus relatively faster growing at low salinity and O. mossambicus at the higher salinities. The hybrids revealed high average positive heterosis for weight gain (1.24) and biomass gain (1.33) but less for FCR (1.08). Regression analyses of relative weight and biomass gain showed highly significant correlations with salinity. The hybrid was superior to O. mossambicus at all salinities and to O. niloticus at salinities above 10 ppt. Survival of O. niloticus was lower than the other genotypes at 22.5 and 30 ppt due to susceptibility to disease and possibly also stress. The implications for the development of Tilapia for brackish water aquaculture are discussed.
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genetic manipulation of sex ratio for the large scale production of all male Tilapia oreochromis niloticus
Canadian Journal of Fisheries and Aquatic Sciences, 1997Co-Authors: G C Mair, Jose S Abucay, T A Abella, J A Beardmore, D O F SkibinskiAbstract:Nous decrivons les resultats d'un programme d'amelioration genetique du Tilapia du Nil, Oreochromis niloticus, en incorporant l'inversion du sexe des mâles en femelles induite par les oestrogenes et l'analyse de la progeniture pour produire des nouveaux genotypes mâles 'YY'. Les mâles de genotype 'YY' se sont reveles aussi viables et fertiles que les mâles normaux XY et le sex-ratio moyen de leur progeniture comportait 95,6% de mâles. Bien que ces resultats confirmaient l'hypothese d'une determination du sexe a predominance monofactorielle, il semble y avoir un fondement genetique pour l'apparition occasionnelle de femelles dans la progeniture des mâles 'YY'. Il est probable que ces femelles proviennent de l'action de plusieurs genes autosomiques modifiant le sexe. Nous signalons le premier cas de feminisation de genotypes YY chez le Tilapia et de production massive de mâles 'YY' par croisement YY x YY, ce qui rend inutile l'analyse de la progeniture, tâche longue et fastidieuse, pour distinguer les genotypes mâles XY et YY. Cette methode permet la production massive a l'echelle commerciale de mâles 'YY' et de leur progeniture entierement mâle, que l'on appelle Tilapias genetiquement mâles. Nous avons conclu que la technologie mâle fournit une solution fiable et robuste au probleme serieux et repandu de la maturation sexuelle precoce, de la reproduction non voulue et de la surpopulation dans la culture du Tilapia.
Eduard Kuhn - One of the best experts on this subject based on the ideXlab platform.
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characterization of iodothyronine outer ring and inner ring deiodinase activities in the blue Tilapia oreochromis aureus
Endocrinology, 1997Co-Authors: K Mol, Theo J. Visser, Serge Van Der Geyten, Veerle Darras, Eduard KuhnAbstract:The presence of iodothyronine deiodinases was investigated in the different tissues of blue Tilapia (Oreochromis aureus), and their biochemical properties were compared with those of mammalian deiodinases. High-Km rT3 outer ring deiodination (ORD) was observed in Tilapia kidney, low-Km T4 ORD in liver, and low-Km T3 inner ring deiodination (IRD) in brain and gill. The rT3 ORD activity in Tilapia kidney has a very similar substrate specificity as rat liver type I iodothyronine deiodinase but is much less sensitive to inhibition by propylthiouracil, iodoacetic acid, and aurothioglucose. Tilapia liver T4 ORD activity and Tilapia brain and gill T3 IRD activities show very similar substrate specificities as well as similar inhibitor sensitivities as rat type II and type III iodothyronine deiodinase, respectively. The optimal pH of the Tilapian enzymes is 6-7, and the optimal incubation temperature is approximately 37 C. All Tilapia deiodinases are stimulated by dithiothreitol, but the optimal DTT concentrations are generally lower than those required by the corresponding rat enzymes. The apparent Km values of the various Tilapia deiodinases for their preferred substrate are in the same range as for the corresponding rat enzymes. Based on these findings, we conclude that fish deiodinases are more similar to mammalian deiodinases than generally accepted.
K Mol - One of the best experts on this subject based on the ideXlab platform.
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characterization of iodothyronine outer ring and inner ring deiodinase activities in the blue Tilapia oreochromis aureus
Endocrinology, 1997Co-Authors: K Mol, Theo J. Visser, Serge Van Der Geyten, Veerle Darras, Eduard KuhnAbstract:The presence of iodothyronine deiodinases was investigated in the different tissues of blue Tilapia (Oreochromis aureus), and their biochemical properties were compared with those of mammalian deiodinases. High-Km rT3 outer ring deiodination (ORD) was observed in Tilapia kidney, low-Km T4 ORD in liver, and low-Km T3 inner ring deiodination (IRD) in brain and gill. The rT3 ORD activity in Tilapia kidney has a very similar substrate specificity as rat liver type I iodothyronine deiodinase but is much less sensitive to inhibition by propylthiouracil, iodoacetic acid, and aurothioglucose. Tilapia liver T4 ORD activity and Tilapia brain and gill T3 IRD activities show very similar substrate specificities as well as similar inhibitor sensitivities as rat type II and type III iodothyronine deiodinase, respectively. The optimal pH of the Tilapian enzymes is 6-7, and the optimal incubation temperature is approximately 37 C. All Tilapia deiodinases are stimulated by dithiothreitol, but the optimal DTT concentrations are generally lower than those required by the corresponding rat enzymes. The apparent Km values of the various Tilapia deiodinases for their preferred substrate are in the same range as for the corresponding rat enzymes. Based on these findings, we conclude that fish deiodinases are more similar to mammalian deiodinases than generally accepted.
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Characterization of iodothyronine outer ring and inner ring deiodinase activities in the blue Tilapia, Oreochromis aureus
'The Endocrine Society', 1997Co-Authors: K Mol, Van Der Geyten Serge, Darras Veerle, Tj Visser, Kühn EduardAbstract:The presence of iodothyronine deiodinases was investigated in the different tissues of blue Tilapia (Oreochromis aureus), and their biochemical properties were compared with those of mammalian deiodinases. High-Km rT3 outer ring deiodination (ORD) was observed in Tilapia kidney, low-Km T4 ORD in liver, and low-Km T3 inner ring deiodination (IRD) in brain and gill. The rT3 ORD activity in Tilapia kidney has a very similar substrate specificity as rat liver type I iodothyronine deiodinase but is much less sensitive to inhibition by propylthiouracil, iodoacetic acid, and aurothioglucose. Tilapia liver T4 ORD activity and Tilapia brain and gill T3 IRD activities show very similar substrate specificities as well as similar inhibitor sensitivities as rat type II and type III iodothyronine deiodinase, respectively. The optimal pH of the Tilapian enzymes is 6-7, and the optimal incubation temperature is approximately 37 C. All Tilapia deiodinases are stimulated by dithiothreitol, but the optimal DTT concentrations are generally lower than those required by the corresponding rat enzymes. The apparent Km values of the various Tilapia deiodinases for their preferred substrate are in the same range as for the corresponding rat enzymes. Based on these findings, we conclude that fish deiodinases are more similar to mammalian deiodinases than generally accepted.status: publishe
Noel Verjan - One of the best experts on this subject based on the ideXlab platform.
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experimental early pathogenesis of streptococcus agalactiae infection in red Tilapia oreochromis spp
Journal of Fish Diseases, 2016Co-Authors: Carlos Iregui, J Comas, Gersson Vasquez, Noel VerjanAbstract:Streptococcus agalactiae causes a severe systemic disease in fish, and the routes of entry are still ill-defined. To address this issue, two groups of 33 red Tilapia Oreochromis spp. each of 10 g were orally infected with S. agalactiae (n = 30), and by immersion (n = 30), six individuals were control-uninfected fish. Three Tilapias were killed at each time point from 30 min to 96 h post-inoculation (pi); controls were killed at 96 h. Samples from most tissues were examined by haematoxylin-eosin (HE only intestine from fish infected by gavage was evaluated by transmission electron microscopy. The results of both experiments suggest that the main entry site of S. agalactiae in Tilapia is the gastrointestinal epithelium; mucus seems to play an important defensive role, and environmental conditions may be an important predisposing factor for the infection.
Veerle Darras - One of the best experts on this subject based on the ideXlab platform.
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characterization of iodothyronine outer ring and inner ring deiodinase activities in the blue Tilapia oreochromis aureus
Endocrinology, 1997Co-Authors: K Mol, Theo J. Visser, Serge Van Der Geyten, Veerle Darras, Eduard KuhnAbstract:The presence of iodothyronine deiodinases was investigated in the different tissues of blue Tilapia (Oreochromis aureus), and their biochemical properties were compared with those of mammalian deiodinases. High-Km rT3 outer ring deiodination (ORD) was observed in Tilapia kidney, low-Km T4 ORD in liver, and low-Km T3 inner ring deiodination (IRD) in brain and gill. The rT3 ORD activity in Tilapia kidney has a very similar substrate specificity as rat liver type I iodothyronine deiodinase but is much less sensitive to inhibition by propylthiouracil, iodoacetic acid, and aurothioglucose. Tilapia liver T4 ORD activity and Tilapia brain and gill T3 IRD activities show very similar substrate specificities as well as similar inhibitor sensitivities as rat type II and type III iodothyronine deiodinase, respectively. The optimal pH of the Tilapian enzymes is 6-7, and the optimal incubation temperature is approximately 37 C. All Tilapia deiodinases are stimulated by dithiothreitol, but the optimal DTT concentrations are generally lower than those required by the corresponding rat enzymes. The apparent Km values of the various Tilapia deiodinases for their preferred substrate are in the same range as for the corresponding rat enzymes. Based on these findings, we conclude that fish deiodinases are more similar to mammalian deiodinases than generally accepted.
